/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.extensions.protobuf;



import com.google.protobuf.ByteString;

import com.bff.gaia.unified.sdk.coders.AtomicCoder;

import com.bff.gaia.unified.sdk.coders.Coder;

import com.bff.gaia.unified.sdk.coders.CoderException;

import com.bff.gaia.unified.sdk.util.VarInt;

import com.bff.gaia.unified.sdk.values.TypeDescriptor;

import com.bff.gaia.unified.vendor.guava.com.google.common.io.ByteStreams;



import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;



/**

 * A {@link Coder} for {@link ByteString} objects based on their encoded Protocol Buffer form.

 *

 * <p>When this code is used in a nested {@link Coder.Context}, the serialized {@link ByteString}

 * objects are first delimited by their size.

 */

public class ByteStringCoder extends AtomicCoder<ByteString> {



  public static ByteStringCoder of() {

    return INSTANCE;

  }



  /** ************************ */

  private static final ByteStringCoder INSTANCE = new ByteStringCoder();



  private static final TypeDescriptor<ByteString> TYPE_DESCRIPTOR =

      new TypeDescriptor<ByteString>() {};



  private ByteStringCoder() {}



  @Override

  public void encode(ByteString value, OutputStream outStream) throws IOException, CoderException {

    encode(value, outStream, Context.NESTED);

  }



  @Override

  public void encode(ByteString value, OutputStream outStream, Context context)

      throws IOException, CoderException {

    if (value == null) {

      throw new CoderException("cannot encode a null ByteString");

    }



    if (!context.isWholeStream) {

      // ByteString is not delimited, so write its size before its contents.

      VarInt.encode(value.size(), outStream);

    }

    value.writeTo(outStream);

  }



  @Override

  public ByteString decode(InputStream inStream) throws IOException {

    return decode(inStream, Context.NESTED);

  }



  @Override

  public ByteString decode(InputStream inStream, Context context) throws IOException {

    if (context.isWholeStream) {

      return ByteString.readFrom(inStream);

    }



    int size = VarInt.decodeInt(inStream);

    // ByteString reads to the end of the input stream, so give it a limited stream of exactly

    // the right length. Also set its chunk size so that the ByteString will contain exactly

    // one chunk.

    return ByteString.readFrom(ByteStreams.limit(inStream, size), size);

  }



  @Override

  protected long getEncodedElementByteSize(ByteString value) throws Exception {

    int size = value.size();

    return (long) VarInt.getLength(size) + size;

  }



  @Override

  public void verifyDeterministic() {}



  /**

   * {@inheritDoc}

   *

   * <p>Returns true; the encoded output of two invocations of {@link ByteStringCoder} in the same

   * {@link Coder.Context} will be identical if and only if the original {@link ByteString} objects

   * are equal according to {@link Object#equals}.

   */

  @Override

  public boolean consistentWithEquals() {

    return true;

  }



  /**

   * {@inheritDoc}

   *

   * <p>Returns true. {@link ByteString#size} returns the size of an array and a {@link VarInt}.

   */

  @Override

  public boolean isRegisterByteSizeObserverCheap(ByteString value) {

    return true;

  }



  @Override

  public TypeDescriptor<ByteString> getEncodedTypeDescriptor() {

    return TYPE_DESCRIPTOR;

  }

}